test(integration): re-enable some tests by renaming their filename

[windmgc]

Summary

It seems some of the test files are not ending with a _spec suffix in their file names.
Thus maybe they're not tested for a long time...

Checklist

• The Pull Request has tests
• There's an entry in the CHANGELOG
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Full changelog

• re-enable some tests by renaming their filename

[windmgc]

Rename the following spec files as they seem useful:

• spec/01-unit/19-hybrid/04-negotiation_spec.lua
• spec/02-integration/04-admin_api/12-plugins-conf_spec.lua
• spec/02-integration/09-hybrid_mode/08-lazy_export_spec.lua
• spec/02-integration/11-dbless/03-config_persistence_spec.lua
• spec/03-plugins/26-prometheus/06-hybrid-mode_metrics_spec.lua

Delete one spec file as it seems deprecated

• spec/02-integration/04-admin_api/18-worker-events.lua (There was an age when worker-events is a plugin? interesting)

[windmgc]

Add an action step in Lint, Doc and Unit tests to check spec files spelling.

Check for a preview result here: https://github.com/Kong/kong/actions/runs/3640543353/jobs/6145358948

[flrgh]

(There was an age when worker-events is a plugin? interesting)

Fun fact: it's actually a test fixture that is still around. Nifty way of testing internal features by throwing them in a dummy plugin handler.

[flrgh]

👍 lgtm, always appreciate more tests :)

[flrgh]

Not merging quite this moment because CI is currently ❌ for master, but as far as I'm concerned it's good to merge once that is taken care of.